Hydrostatic Guide Device Variable Orifice Stiffness

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Solution Overview

Problem

Conventional hydrostatic guide devices require high machining and assembly accuracy to ensure stiffness, increasing manufacturing costs and man-hours.

Innovation Solution

A hydrostatic guide device with variable orifices and hydrostatic pockets that maintain stiffness regardless of machining and assembly accuracy variations, using a hydraulic pump to regulate fluid pressure and create a non-contact sliding state between guide faces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional hydrostatic guide devices use fixed orifices to regulate fluid pressure, then guidance stiffness can be improved, but machining accuracy and assembly accuracy must be very high to ensure stable stiffness, which increases manufacturing cost and man-hours

Engineering Contradiction:
Improveguidance stiffnessVSAvoidmachining accuracy and assembly accuracy
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The patent applies the dynamics principle by replacing fixed orifices with variable orifices that automatically adjust their opening size in response to changes in the gap between guide faces. This dynamic adjustment allows the system to maintain stable guidance stiffness even when machining or assembly accuracy varies, as the variable orifices compensate for gap variations by regulating fluid pressure accordingly.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements feedback through the variable orifice mechanism that senses gap changes between guide faces and automatically adjusts fluid pressure to maintain constant stiffness. The system continuously monitors the gap condition and provides corrective action through pressure regulation, eliminating the need for high machining and assembly accuracy while ensuring stable guidance performance.

Inventive Principle:
Principle #23Feedback

2Reliability

If high machining accuracy and assembly accuracy are required to ensure stable guidance stiffness, then guidance stiffness can be maintained, but manufacturing cost and man-hours increase

Engineering Contradiction:
Improvestable guidance stiffnessVSAvoidmanufacturing cost and man-hours
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies self-service through the variable orifice system that automatically regulates fluid pressure based on gap conditions without requiring external intervention or high-precision manufacturing. The system serves itself by detecting gap variations and adjusting pressure accordingly, thereby maintaining reliable guidance stiffness while allowing for standard, cost-effective machining and assembly processes.

Inventive Principle:
Principle #25Self-service

3Reliability

If variable orifices are used to regulate fluid pressure, then guidance stiffness becomes stable regardless of accuracy variations, but device complexity increases

Engineering Contradiction:
Improvestable guidance stiffnessVSAvoidorifice regulation mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses the variable orifice as an intermediary element between the fluid supply and the hydrostatic pockets. This intermediary component automatically mediates pressure regulation in response to gap changes, providing stable guidance stiffness without requiring complex external control systems. The variable orifice acts as a simple yet effective mediator that translates gap variations into appropriate pressure adjustments.

Inventive Principle:
Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Ensures stable high stiffness between guide faces with reduced manufacturing complexity and cost, allowing for accurate machining operations.

Implementation Method 1

a hydraulic pump (33), variable orifices (24), and hydrostatic pockets (34, 35)... a first fluid pressure (P1) supplied into the hydrostatic pocket (34) through the variable orifice (24), and a second fluid pressure (P2) supplied into the hydraulic pocket (35)

Methodology Applied
Scientific EffectHydraulic pressure: Pressure Increase

Implementation Method 2

a first fluid pressure (P1) supplied into the hydrostatic pocket (34) through the variable orifice (24)

Methodology Applied
Scientific EffectFluid flow regulation through variable orifice: Pressure Drop

Implementation Method 3

hydrostatic pockets, which are recesses, are formed in one of opposed faces of the two members that move relative to each other, and a fluid such as air or oil is spouted from the hydrostatic pockets to form a fluid outflow layer having a predetermined thickness between the two members

Methodology Applied
Scientific EffectHydrostatic lubrication: Lubrication

Implementation Method 4

a first urging force (F1) generated by the first fluid pressure (P1), and a second urging force (F2) generated by the second fluid pressure (P2)... the first urging force (F1) and the second urging force (F2) are balanced with each other

Methodology Applied
Scientific EffectFluid pressure force: Pressure Increase

Data Source

PatentEP2740952B1Hydrostatic guide device and machine tool using the hydrostatic guide device
Publication Date: 2019.01.16 JTEKT CORP
  • EP2740952B1 patent drawingFigure 1
  • EP2740952B1 patent drawingFigure 2~3
  • EP2740952B1 patent drawingFigure 4~5

AI summary

A hydrostatic guide device includes: a fixed member (19) having vertical guide faces (16a, 17a); a movable member (14) having vertical slide faces (14a1, 14a2); a fluid supply device (33); a hydrostatic pocket (34) to which a first fluid pressure (P1) based on a dimension of a gap (L1) is applied, and that urges the movable member with a first urging force (F1); and a hydraulic pocket (35) to which a second fluid pressure (P2) based on a dimension of a gap (L2) is applied, and that urges the movable member with a second urging force (F2). A variation of the second fluid pressure (P2) is smaller than a variation of the first fluid pressure (P1). When the first urging force and the second urging force are balanced with each other in a horizontal direction, the gap (L1) between the vertical guide face (16a) and the vertical slide face (14a1) becomes a set value.